Many factors can impact a person's risk of having a stroke within 10 years. Important risk factors include age, gender, ethnicity, family history, previous history of stroke or transient ischemic attack (ministroke), high blood pressure, high cholesterol, smoking, diabetes, obesity, heart disease, increased homocysteine levels, sickle cell anemia, and use of birth control pills or hormone therapy. Some risk factors, including gender, age, and heredity, cannot be controlled. The more risk factors a person has, the greater his/her risk of having a stroke.

A stroke occurs when there is a sudden interruption of blood flow and oxygen to areas in the brain. A stroke may occur if a blood clot or other particles (such as cholesterol) clogs an artery that supplies blood to the brain or if a blood vessel in the brain leaks or breaks open. It may also occur if bleeding starts in a large artery on or near the membrane surrounding the brain and spills into the space between the surface of the brain and skull.

A stroke develops suddenly, usually in a matter of minutes, and causes symptoms, such as paralysis, numbness or weakness often affecting one side of the body, confusion, dizziness, speech problems, and loss of vision. These symptoms may come and go, go away completely, or worsen over the course of several hours. In some cases, a stroke may be fatal or it may lead to long-term or permanent brain damage.

Risk assessment tools, or calculators, may help individuals who are older than 20 years of age estimate their risks of having strokes. There are many different risk assessment tools available online, and they vary slightly. In general, individuals are asked to enter important health information, such as their age, gender, height, weight, blood pressure, and cholesterol levels. Based on the information provided, the calculator estimates the person's risk of having a stroke in the next 10 years.

It is important to note that a 10-year stroke risk assessment tool only provides an estimate of a person's risk. If a person's risk is low it does not guarantee that he/she will not have a stroke. Likewise, if a person's risk is high, it does not necessarily mean that he/she will have a stroke.

These tools should not replace regular visits to the doctor. They are intended to be used in addition to regular medical checkups.

General: There are several factors that increase a person's risk of having a stroke, including age, gender, ethnicity, family history, previous history of stroke or transient ischemic attack (ministroke), high blood pressure, high cholesterol, smoking, diabetes, obesity, heart disease, increased homocysteine levels, sickle cell anemia, and use of birth control pills or hormone therapy. The more risk factors a person has, the greater his/her risk of having a stroke.

Age: A stroke can happen to anyone, but the risk of stroke increases with age. After the age of 55, the risk of stroke doubles every 10 years.

Birth control pills and hormone therapy: The risk of stroke is higher among women who take birth control pills (oral contraception), especially among smokers and those older than 35. Lower dosages may help decrease the risk of stroke. Hormone replacement therapy (HRT) used during menopause also carries an increased risk of stroke.

Diabetes: Diabetes is a major risk factor for a stroke. This is because diabetes may damage arteries, predisposing diabetics to atherosclerosis (hardening of the arteries). Overall, the risk of heart disease (including stroke) is two-and-a-half times higher in men and women with diabetes compared to people without diabetes.

Elevated homocysteine levels: The amino acid homocysteine occurs naturally in the body. Elevated homocysteine levels in the blood (a condition called hyperhomocysteinemia) have been linked to a high risk of coronary heart disease and stroke. Homocysteine stimulates the growth of cells that help form plaque (deposits of protein and cholesterol) in blood vessels, encouraging blood clotting and blockages in the vessels.

Deficiencies in folic acid (folate), vitamin B6, or vitamin B12 may lead to hyperhomocysteinemia. Patients with kidney failure who are undergoing dialysis also have an increased risk of developing hyperhomocysteinemia. However, researchers have not discovered exactly why this condition may develop in dialysis patients.

Hyperhomocysteinemia does not cause any symptoms. Therefore, the American Heart Association (AHA) recommends regular homocysteine testing in patients who have high risks of developing heart disease.

Gender: Strokes are more common in men than women. This is because men are more likely to develop high blood pressure and heart disease than women. However, more women than men die from stroke. Women tend to be older than men when a stroke occurs and are less likely to recover due to age and fragility. Also, hormonal replacement therapy (HRT), birth control pills, and pregnancy may increase the risk of stroke in women.

Family history: If a relative in a patient's immediate family, such as a parent or sibling, has had a stroke, a patient's risk of stroke is increased.
This is because many risk factors for a stroke, such as high blood pressure, heart disease, and obesity, may be related to a person's biological makeup.

Heart disease: Heart disease, or coronary heart disease (CAD), may increase the risk of a stroke. Coronary heart diseases include congestive heart failure, a previous heart attack, an infection of a heart valve (endocarditis), a particular type of abnormal heart rhythm (atrial fibrillation or AF), aortic or mitral valve disease, valve replacement, or a hole in the upper chambers of the heart (patent foramen ovale). AF increases stroke risk up to six times, because the abnormal pumping of the heart allows blood to pool within the chamber and form clots, which are then pumped into the bloodstream and travel throughout the body and potentially into the brain. About 15% of all people who have strokes also have AF. Additionally, atherosclerosis in blood vessels around the heart may indicate atherosclerosis in other blood vessels, including those in and around the brain.

High blood pressure (hypertension): High blood pressure increases a person's risk of having a stroke. High blood pressure may weaken and damage blood vessels in and around the brain, making them vulnerable to atherosclerosis (hardening of the arteries) and bleeding. People with high blood pressure are four to six times more likely to have a stroke than those who have normal blood pressure.

High cholesterol: High cholesterol levels, especially low-density lipoprotein (LDL) cholesterol ("bad cholesterol"), may increase the risk of atherosclerosis. In excess, LDLs and other materials build up on the lining of artery walls, where they may harden into plaques. The blood must now force its way through tiny openings. When the blood flow is completely blocked, a lack of oxygen causes cells to die and may cause a stroke in the brain.

Obesity: A high body mass index (BMI), or the amount of fat on the body, increases the chances of developing high blood pressure, heart disease, atherosclerosis, and diabetes, all of which increase risk factors associated with stroke. People who have excessive abdominal fat have a particularly high risk of developing heart disease and stroke. This is because being overweight puts extra strain on the heart, leading to increased blood pressure, high cholesterol and triglyceride levels, and decreased high-density lipoprotein (HDL or "good cholesterol") levels.

Previous stroke or transient ischemic attack (TIA): A prior stroke or a transient ischemic attack (ministroke) increases the chances of another stroke within five years by about 25-40%. A person should seek immediate medical treatment if he/she experiences symptoms of TIA, such as: sudden numbness or weakness of the face, arm, or leg, especially on one side of the body; sudden confusion; trouble speaking or understanding; sudden trouble seeing in one or both eyes; sudden difficulty walking; dizziness; loss of balance or coordination; and sudden, severe headache with no known cause that lasts several minutes to 24 hours. TIAs are often warning signs that a person is at risk of experiencing a serious stroke in the future.

Ethnicity: African Americans are almost twice as likely to have strokes as Caucasians. Hispanics or Asian/Pacific Islanders also have a higher risk of stroke than Caucasians. African Americans have increased risks of developing high blood pressure, diabetes, and obesity, all of which are risk factors for a stroke. Researchers believe that a person's biological makeup as well as diet, lifestyle factors, and access to healthcare may contribute to his/her risk of having a stroke.

Sickle cell anemia: Sickle cell anemia occurs when a person is born with abnormally shaped blood cells. Because the blood cells are irregularly shaped, they are more likely to block blood vessels, which can lead to a stroke. Stroke is the second leading cause of death in people who are younger than 20 years of age who have sickle cell anemia.

Smoking: Smoking cigarettes also increases a person's risk of having a stroke. Smoking contributes to plaque build up in the arteries. Nicotine, found in cigarettes, makes the heart work harder by increasing heart rate and blood pressure. The carbon monoxide in cigarette smoke replaces oxygen in the blood, decreasing the amount of oxygen delivered to the brain and the rest of the body.

Alcohol consumption increases the risk of developing a stroke. Therefore, it is recommended that men drink no more than two alcoholic drinks per day and women drink no more than one alcoholic drink per day.

The use of illicit drugs, such as cocaine and methamphetamine, as well as some prescription stimulant drugs (amphetamines) may also increase the risk of stroke.

In order to use a stroke risk assessment tool, individuals need to know information about their health. Most calculators ask people to enter their age, gender, height, and weight, as well any pre-existing medical conditions (such as diabetes). Many calculators also ask people to enter their blood pressure and cholesterol levels (total, LDL, HDL, and triglycerides). Individuals can ask their doctors for these test results if they do not know them. In order to get the most accurate results, it is important that individuals enter their own, up-to-date information.

After a person enters his/her medical information, the risk assessment tool provides the person's theoretical estimated risk of experiencing a stroke in the next 10 years. It is important to note that this is just an estimate. If a person's risk is low it does not guarantee that he/she will not have a stroke. Likewise, if a person's risk is high, it does not necessarily mean that he/she will have a stroke.

Based on the person's responses, the risk assessment tool provides suggestions on how to lower his/her risk of having a stroke. For instance, obesity and smoking are risk factors that a person can control. By losing weight and quitting smoking, a person may decrease his/her risk of having a stroke.

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.